Asian Hornet - Vespa velutina nigrithorax - Frelon asiatique

Asian Hornet - Vespa velutina nigrithorax - Frelon asiatique - France

Asian Hornet in France

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Asian Hornet - Vespa velutina nigrithorax - Frelon asiatique

First observed in 2005 the Asian Hornet is thought to have arrived in France from China in 2004, in a container of pottery passing through the port of Bordeaux. Since that date its spread throughout the neighboring regions has been rapid and often, in the initial stages, follows rivers and other watercourses. In fact it will never be found far from a source of water even if that is only a small pond.

Slightly smaller than the European Hornet, with queens up to 30mm, and workers up to 25mm, they are easily recognised by their appearance and difficult to confuse with any other species. The thorax is a velvety black / dark brown with brown abdominal segments bordered with a fine yellowy orange band. Only the 4th segment is almost entirely a yellowy orange. The legs are brown with yellow ends and the head is black with an orange yellow face.

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Asian Hornet - France

The nest is built using “paper mâché” made from chewed tree and plant material. It is composed of several wafers of cells surrounded by a double skinned envelope of broad reinforced paper scales, striated with beige and brown. Unlike the European Hornet where the entrance is on or near the bottom, the entrances are on the sides, (see photo). Another difference is that the European hornet makes its nest in cavities, whereas the Asian Hornet makes a suspended nest, usually in a tree but sometimes in a large open roof space. This is easy to see; it is spherical or oval and can be as much as 1 metre in height, 80cm in diameter and generally between 4 and 15 metres from the ground. It is rare for it to use a hollow in a tree or cavity in the ground. Unfortunately the nest is sometimes hidden by the trees foliage and as its comings and goings are more discrete than the European hornet their presence isn’t always noticed until the leaves begin to fall in early autumn.

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Photo_Queen-Asian-Hornet-constructing-nest_France.

Photos above: Queen Asian Hornet constructing her initial nest.

Although the European Hornet will attack and kill the odd honey bee in small numbers as a food source for their larvae it does not present a problem, however the situation is far worse with the Asian Hornet and can lead to the destruction of the entire colony. The Asian Hornets will station themselves hovering at about 30cm from the entrance to the honey bee colony where they pounce on returning bees that are carrying pollen, fall to the ground with them, cut of the head with their mandibles and transport them to a tree. Here they remove the wings and legs before making a little “meat ball” that they transport back to their nest to feed their own larvae. Having found a colony, often a bee hive, they will sometimes arrive in numbers to take an easy food source one after another. The consequences for the bee colony can be catastrophic, if the flow of pollen into the hive is severely disrupted. Over time it will result in the death of some or all of the larvae and the queen will either stop or reduce her egg production. This will lead to the decline of the colony, aging bees will die with few or no replacements to take their place. At best the colony will be vulnerable to disease due to the dead larvae and the overall weakness of the colony will lead to robbing. The colony will have little hope of over wintering.

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Photos above: Asian hornets nest suspended in a tree showing the entrance slits.

Scale of risks for honey bees:
2 Hornets per hive: A disturbance is noted but the hive activity is maintained.
3 to 5 Hornets per hive: The disturbance will be important.
More than 5 Hornets per hive: The colony will be condemned in the long term unless the hornets are caught and killed or the hive is moved to another area.

Risk to humans from this species is minimal except when and if they consider their nest to be under threat, otherwise they are more timid than the European Hornet and their sting is no worse than that from an ordinary wasp.

They are only out during daylight hours unlike the European Hornet that will also fly at night.

As with all the social wasps (common Wasps, Hornets and Polistes), the colonies of the Asian Hornet live only one year and it is only fertilised queens survive the winter in hibernation.

Solutions:
Small nests with only a queen at the beginning of the season, (as in the photos at the top), can be destroyed using a powerful aerosol wasp spray with caution.

Larger nests should be destroyed as a matter of urgency by a competent person that is equipped for the job. Your local Pompiers may perform this service, if not they will be able to give you the contact details of someone that will.

Purpose made traps as illustrated can be placed anywhere where the Asian Hornet are thought to be present and importantly near to bee hives. The dimensions are important.

Materials you will need to make a trap.

1 x 2 Litre Plastic bottle.
1 x 100mm PVC joint (for 100mm PVC pipe).
1 x 100mm PVC screw end cap for joint that will allow you to change the attractant without releasing any Hornets.
1 piece of metal grill to put over the attractant. This will prevent bees and insects falling in the liquid.
1 piece of wood 20cm x 20cm.
Some steel wire, approx 60cm.
PVC glue.
Some silicone sealant.

Translation of diagram / document terms and wording..

Toit carré en bois de 200 x 200mm
Square wood roof 200 x 200mm

Fil de fer de suspension et de fixation entonnoir / chambre
Steel wire for fixing and suspending the trap.

La taille de l’orifice ne permet pas à V.Crabro de pénétrer dans le piège
The diameter of the aperture prevents the European Hornet from entering.

Chambre de capture
Capture space.

Grille de protection
Wire mesh grill to prevent insects falling in the attractant.

5.5mm Trou de sortie pour les autres espèces
5.5mm exit holes for other species to escape. e.g. honey bees

Appât
Attractant. Sugar water, beer, jam etc.

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